With development of an Internet Protocol, Internet Protocol (IP) network, more and more applications use the IP network to perform data transmission. Data transmission of applications such as multimedia conferencing, real-time online gaming, and IP Television (IPTV) has a point-to-multipoint (or multipoint-to-multipoint) feature.
Compared with a unicast data transmission mode of the IP network, an IP multicast technology implements point-to-multipoint data transmission in the IP network. For multiple data receiving nodes, it is unnecessary to replicate all traffic of data at a sending end; instead, traffic is replicated at a corresponding node as required according to an IP forwarding path in the network. On the whole, only one piece of data is transmitted on any link in the network, until the data arrives at the receiving nodes. Therefore, compared with IP unicast transmission, IP multicast transmission has a remarkably lower requirement for network bandwidth, so that highest data transmission efficiency is achieved in the network. IP multicast transmission requires cooperation of a control plane in the network, which is completed by a corresponding multicast protocol, for example, Protocol Independent Multicast-Sparse Mode (PIM-SM) or Protocol Independent Multicast Source Specific Multicast (PIM-SSM). After protocol interaction, the IP network establishes a transmission path for multicast data, thereby achieving objectives of an optimal path and least bandwidth usage.
However, in terms of supporting real-time applications such as IPTV and streaming media, there are still restrictions for IP multicast, such as a bandwidth guarantee and failover, which restrict large-scale deployment of the applications. As the Multi Protocol Label Switching (MPLS) technology is deployed on a large scale, failover can be implemented and bandwidth requirements can be met. Therefore, the Point-to-MultiPoint (P2MP) multicast technology base on MPLS has become a hot topic currently.
Currently, the MPLS P2MP technology mainly includes two types: Resource Reservation Protocol (RSVP) P2MP and multicast Label Distribution Protocol (mLDP) P2MP. The former is an extension based on a point-to-point RSVP protocol, and the latter is an extension based on a point-to-point LDP protocol. A purpose of the MPLS P2MP technology is to establish a point-to-multipoint (or multipoint-to-multipoint) forwarding path for data forwarding.
According to an existing solution, in a P2MP-based multicast Virtual Private Network (VPN) application proposed by an Internet Engineering Task Force (IETF) draft, a core network establishes RSVP P2MP Path, while mLDP is used for access between each Provider Edge (PE) node and each Customer Edge (CE), and multicast traffic of a private network is transmitted through mLDP P2MP forwarding paths at two ends and a core RSVP P2MP forwarding path. In this way, mLDP may access P2MP. However, this application is an application that accesses the VPN. VPN negotiation needs to be performed at the control plane based on a complicated protocol, and a forwarding entry of a PE node must be established based on VPN information. Therefore, this solution is not applicable to a P2MP multicast scenario of a non-VPN application. Furthermore, in an existing multicast scenario, a PE node must perform mLDP protocol processing, and implementation thereof is complicated, and when a PE device does not support mLDP, deployment cannot be implemented.